1. Field of Invention
This invention relates to a drill guide apparatus which keeps spade drills and drill extension rods on a straight course while drilling deep holes. Thus it prevents the drill from wobbling and drifting.
2. Description of the Related Art
In general, craftsmen in the carpentry trade have been using two types of tools to drill holes. One is a hole saw, and the other is the spade drill.
Customarily, the hole saw is used for holes one inch and larger. However, hole saws do come in smaller sizes. When holes from ¼″ of an inch up to 1½″ are desired, the spade drill is utilized. These tools differ in form, but they both, basically, have the same function. This function is to make a perfectly round hole in wood and other material. The spade drill has an advantage over the hole saw because of its design. Unlike the hole saw, the spade drill is able to use a drill extension rod and thus drill deeper holes. Conversely, the cup design of the hole saw limits the depth of the hole to about two inches. If attempting to saw more than two inches deep, you will be forced to remove the plug that is left in the hole saw. This invention, the drill guide apparatus, is used in conjunction with the spade drill; so that it will be the main focus. The spade drill has been around for many years with U.S. Pat. No. 2,782,824 issued February, 1957; and U.S. Pat. No. 2,794,468 issued June, 1957. Since the time that these patents were given, the spade drill has not changed appreciably; and has been serving carpenters as a tool that is reliable. There are, however, drawbacks when using the spade drill because of its design. The hand drill creates torque which, in turn, gives place to drifting and wobbling.
These problems inspired the design of the drill guide apparatus. No longer is it necessary for the workman to rely solely on “eyeballing” the drilling to attempt a straight course through the material. In order to avoid the pitfalls of drift and wobble, this invention utilizes four separate guides that are assembled together. These, in turn, cause the drill to stay on a course that is both parallel and perpendicular. One of the four guides in this embodiment, the insert guide, stabilizes the drill, thus keeping it from wobbling. Another advantage is that the drill will keep its edge life longer due to the flow of cut being even. In order to operate the system properly, there is only one requirement. The shaft size of the spade drill and the shaft size of one drill extension rod must enable the enjoined tools to fit inside the insert guide. While the spade drills are customarily manufactured with a standard shaft size of 5/32″. The drill extension rods are manufactured with no set standard. When a drill extension rod that has a 5/32″ shaft is utilized, it will fit into the insert guide. If you need to drill deeper than the one drill extension rod, you would simply add other drill extension rods to the one that fits into the insert guide. In addition, you have the option of manufacturing the insert guides to fit any size shaft you like. As for the drill extension rod, the end that goes in the hand drill side is usually the same size as the shaft while the other end is designed to accept a shaft size of about 5/32″. The outside head diameter is about ½″ tapering to the shaft size. With the 5/32″ hole being about ¾″ deep in the end of the drill extension rod, there is a second requirement. The drilled hole has to be larger than the head diameter of the drill extension rod, for the ½″ diameter to fit into the drilled hole. If the drill extension rod would not fit, another alternative could be to manufacture the drill extension rod with a smaller head diameter. This drill extension rod would fit smaller spade drill sizes. And, once again, a spade drill is defined as a drill having a cutting edge larger than its shaft (shank).